The present disclosure relates generally to subsea production coolers. More specifically, in certain embodiments the present disclosure relates to subsea production coolers that utilize natural convection and gas lift and associated methods.
Crude oil and other fluids produced from production wells are sometimes produced at temperatures too high for handling by available subsea hardware, for example at temperatures at or above 400° F. These high temperatures may create a thermal strain on hardware on the seafloor and often may require additional cooling of the fluid on the topsides. As a result, it is desirable to cool these fluids to temperatures in the range of 180° F. to 300° F. before they are transported along or from the seafloor.
Conventional subsea cooling techniques utilize un-insulated production piping arranged in sets of hairpin turns or other configurations such as a pyramid convecting freely to the surroundings. Typically, these conventional subsea cooling techniques have very limited ability to adapt to changing flow rates or temperatures of the produced fluids. This may result in excessive cooling, which may be problematic in fluids that are not fully inhibited against hydrate blockage by chemicals.
One type of subsea cooler utilizes coiled tubing surrounded by a shroud to provide a passive cooling system. An example of such a cooler is described in U.S. Patent Application 61/831,880, the entirety of which is hereby incorporated by reference. However, it may be desirable to provide a subsea cooler comprising coiled tubing surrounded by a shroud that is not a completely passive system.